Dyes, inks and their use in ink-jet printing

ABSTRACT

A compound of the Formula (1) and salts thereof:                    
     wherein: 
     D is the residue of a mono-azo chromophore; 
     Z is an optionally substituted nitrogen containing heterocyclic group; 
     R 1  is H or optionally substituted alkyl; 
     the dyes of Formula (1) being free from fibre reactive groups; 
     provided that the compound of Formula (1) is other than the compound of Formula (A):                    
     Also claimed are compositions and inks containing a compound of Formula (1), a process for ink jet printing using the inks and to an ink jet printer cartridge containing the ink.

This invention relates to dyes, to inks and to their use in ink jetprinting (“IJP”).

IJP is a non-impact printing technique in which droplets of ink areejected through a fine nozzle onto a substrate without bringing thenozzle into contact with the substrate.

There are many demanding performance requirements for dyes and inks usedin IJP. For example they desirably provide sharp, non-feathered imageshaving good water-fastness, light-fastness and optical density. The inksare often required to dry quickly when applied to a substrate to preventsmudging, but they should not form a crust over the tip of an ink jetnozzle because this will stop the printer from working. The inks shouldalso be stable to storage over time without decomposing or forming aprecipitate which could block the fine nozzle.

According to a first aspect of the present invention there is provided amono-azo compound of Formula (1) and salts thereof:

wherein:

D is the residue of a mono-azo chromophore;

Z is an optionally substituted nitrogen containing heterocyclic group;

R¹ is H or optionally substituted alkyl;

the dyes of Formula (1) being free from fibre reactive groups;

provided that the compound of Formula (1) is other than the compound ofFormula (A):

R¹ is preferably H or optionally substituted C₁₋₄-alkyl, more preferablyH or C₁₋₄-alkyl optionally substituted by hydroxy, carboxy, sulpho orcyano. Examples include methyl, ethyl, n-propyl, iso-propyl,hydroxyethyl, cyanoethyl, sulphopropyl and carboxyethyl. It isespecially preferred that R¹ is H.

The nitrogen containing heterocyclic group represented by Z ispreferably attached to the triazine ring in Formula (1) by a bond to anitrogen atom in the heterocyclic group.

Z may contain more than one nitrogen atom. Z may also contain otherheteroatoms in addition to nitrogen, for example one or more sulphur oroxygen atom(s).

Z may be a monocyclic or polycyclic nitrogen containing heterocyclicgroup which may be saturated, unsaturated or aromatic. It is preferredhowever that Z is a bicyclic or, more preferably, a monocyclic nitrogencontaining heterocyclic group. It is especially preferred that Z is a 6or more especially a 5 membered monocyclic nitrogen containingheterocyclic group.

Preferably Z is free from primary and secondary amino groups because wehave found that the presence of such groups reduces the light-fastnessof the compounds of Formula (1).

Preferred groups represented by Z include morpholino, pyrrolyl,imidazolyl, isoindolyl, indazolyl, pyrazolyl, pyrrolidinyl, pyrrolinyl,imadazolidinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl, piperidino,piperazinyl, indolinyl, isoindolinyl, isothiazolinone,benzisothiazolinone or tetrahydroisoquinolinyl each of which isoptionally substituted.

Preferred optional substituents on Z include sulpho, carboxy, halogen(preferably chloro) alkoxy (preferably C₁₋₆-alkoxy) or alkyl((preferably C₁₋₆-alkyl) optionally substituted by hydroxy, carboxy orsulpho. Especially preferred optional substituents on Z are C₁₋₄-alkyl,carboxy or sulpho.

It is especially preferred that Z is morpholino or pyrrolidinyloptionally substituted by C₁₋₄-alkyl, carboxy or sulpho.

The mono-azo group represented by D contains one azo group (—N═N—).Preferably D is a group of the Formula (2):

wherein:

Ar is optionally substituted aryl or optionally substituted heteroaryl;and

L is optionally substituted arylene.

Preferred groups represented by Ar contain up to 20, more preferably upto 15 and especially up to 12 carbon atoms.

When Ar is optionally substituted aryl it is preferably optionallysubstituted phenyl, optionally substituted naphthyl or optionallysubstituted indanyl.

When Ar is optionally substituted heteroaryl it is preferably optionallysubstituted pyrazolonyl, optionally substituted pyridonyl (especiallyoptionally substituted hydroxypyridonyl), optionally substitutedthiophenyl, optionally substituted thiazolyl or optionally substitutedbenzisothiazolyl.

Preferably Ar is optionally substituted phenyl or optionally substitutednaphthyl.

Preferred optional substituents on Ar include halogen (especially F andCl), nitro, cyano, —CF₃, —OR², —SR², —NR³R⁴, —C(O)R⁵, —C(O)OR⁶, —SO₂R⁷,—SOR⁸ or C₁₋₆-alkyl optionally substituted by —OH, —SO₃H, —COOH, —PO₃H₂,C₁₋₄-alkoxy or hydroxy-C₁₋₄-alkylene-oxy;

wherein:

R² is H, C₁₋₆-alkyl optionally substituted by —OH, —SO₃H or —COOH, orphenyl optionally substituted by C₁₋₄-alkyl, —OH, —SO₃H, —COOH, —NH₂ or—NO₂;

R³ and R⁴ are each independently H, —CO(C₁₋₆-alkyl), —CONH₂, C₁₋₆-alkyloptionally substituted by —OH, —SO₃H or —COOH, or phenyl optionallysubstituted by C₁₋₄-alkyl, —OH, —SO₃H, —COOH, —NH₂ or —NO₂; or

R³ and R⁴ together with the nitrogen to which they are attached form a5- or 6-membered ring (preferably morpholine or piperazine); and

R⁶, R⁷, R⁸ and R⁹ are each independently C₁₋₆-alkyl or phenyl.

Especially preferred optional substituents on Ar include one or more ofC₁₋₄-alkyl, C₁₋₄-alkoxy, —OH, —COOH, —PO₃H₂, —SO₃H, nitro, —Cl, —F,—CF₃,amino and —COOC₁₋₄-alkyl.

Preferred examples of groups represented by Ar include 2-carboxyphenyl,3,5-dicarboxyphenyl, 2-sulphophenyl, 3-sulphophenyl,2-carboxy-4-sulphophenyl, 3,4-dimethyl-6-sulphophenyl,4-amino-2-hydroxyphenyl, 4-carboxy-2-hydroxyphenyl,1,5-disulphonaphth-2-yl, 1-sulphonaphth-2-yl, 3,6,8-trisulphonapth-2-yl,8-hydroxy-2,4-disulphonaphth-1-yl,1-amino-8-hydroxy-3,6-disulphonaphth-2-yl,2-amino-8-hydroxy-6-sulphonaphth-1-yl,2-amino-8-hydroxy-6-sulphonaphth-7-yl,2-amino-8-hydroxy-3,6-sulphonaphth-1-yl or 6-sulpho-indan-5-yl.

Preferably L is optionally substituted phenylene or optionallysubstituted naphthylene. Preferred optional substituents on L are thepreferred optional substituents as hereinbefore described in relation toAr.

When L is optionally substituted phenylene it is preferably a group ofthe Formula (3):

wherein:

G is sulpho, carboxy, optionally substituted alkyl, optionallysubstituted alkoxy, —CF₃ or —PO₃H₂; and

n is 0 to 4.

Preferably G is —SO₃H, —COOH, —CF₃, optionally substituted C₁₋₄-alkyl,optionally substituted C₁₋₄-alkoxy or —PO₃H₂, more preferably —SO₃H,—COOH or —CF₃ and especially —SO₃H. Preferred optional substituents on Gare selected from —OH, —SO₃H, —COOH and —NH₂, more preferably —OH.

n is preferably 0, 1 or 2, more preferably 1 or 2 and especially 1.

It is especially preferred that when L is of the Formula (3) it is a1,4-phenylene group optionally carrying a substituent represented by Gat the ortho position relative to the azo group in Formula (2).

When L is optionally substituted naphthylene it is preferably of theFormula (4):

wherein:

G is as hereinbefore defined; and

q is 0 to 4.

Preferably q is 1 to 4. Preferably the group of Formula (4) carries atleast one, more preferably two sulpho group(s). It is especiallypreferred that the compound of Formula (4) is of the Formula (5):

wherein:

t is 0 or 1.

When t is 1 in Formula (5) the sulpho group is preferably attached atthe 4- or more preferably the 3-position in the naphthylene ring.Preferably the azo group is attached at the 7-position of thenaphthylene ring in Formula (5).

In a preferred embodiment L is a naphthylene group, preferably a groupof the Formula (5) as hereinbefore described.

It is especially preferred that the compound of Formula (1) is magentain colour.

In view of the foregoing preferences the compound of Formula (1) ispreferably a compound of the Formula (6) or a salt thereof:

wherein:

Ar¹ is optionally substituted phenyl or optionally substituted naphthyl;

Z¹ is an optionally substituted nitrogen containing heterocyclic groupwhich is attached to the triazine ring by a bond to a nitrogen atom inthe heterocyclic group;

R² is H or C₁₋₄-alkyl optionally substituted by —OH, —COOH or —SO₃H; and

t is 0 or 1.

Preferably Z¹ is as hereinbefore defined for Z except the heterocyclicgroup is attached to the triazine ring in Formula (6) by a bond to anitrogen atom in the heterocyclic group. More preferably Z¹ is anoptionally substituted 5 or 6 membered heterocyclic group. It isespecially preferred that Z¹ is free from primary or secondary aminogroups. More especially Z¹ is morpholino or pyrrolidinyl each of whichis optionally substituted by C₁₋₄-alkyl, carboxy or sulpho.

Preferred optional substituents on Ar¹ are as hereinbefore defined inrelation to Ar. It is especially preferred that Ar¹ is phenyl ornaphthyl each of which is optionally substituted by one or more of —OH,—SO₃H, —COOH, —NH₂, C₁₋₄-alkyl, C₁₋₄-alkoxy or nitro.

When t is 1 the floating sulpho group in Formula (1) is preferablyattached at the 3- or 4-position in the napthylene ring. More preferablyt is 1 and the floating sulpho group is attached at the 3-position.

The compounds of Formula (6) provide prints which exhibit a highlight-fastness and good water-fastness when incorporated into inks forink jet printing. The compounds of Formula (6) are also highly solublewhich improves operability and reduces crusting and nozzle blockage wheninks containing the compounds are used in an ink jet printer.

Compounds of the present invention Formula (1) are free from fibrereactive groups. The term fibre reactive group is well known in the artand is described for example in EP 0356014 A1. Fibre reactive groups arecapable, under suitable conditions, of reacting with the hydroxyl groupspresent in cellulosic fibres or with the amino groups present in naturalfibres to form a covalent linkage between the fibre and the dye. Asexamples of fibre reactive groups excluded from the compounds of Formula(1) there may be mentioned aliphatic sulphonyl groups which contain asulphate ester group in beta-position to the sulphur atom, e.g.beta-sulphato-ethylsulphonyl groups, alpha, beta-unsaturated acylradicals of aliphatic carboxylic acids, for example acrylic acid,alpha-chloro-acrylic acid, alpha-bromoacrylic acid, propiolic acid,maleic acid and mono- and dichloro maleic; also the acyl radicals ofacids which contain a substituent which reacts with cellulose in thepresence of an alkali, e.g. the radical of a halogenated aliphatic acidsuch as chloroacetic acid, beta-chloro and beta-bromopropionic acids andalpha, beta-dichloro- and dibromopropionic acids or radicals ofvinylsulphonyl- or beta-chloroethylsulphonyl- orbeta-sulphatoethyl-sulphonyl-endo-methylene cyclohexane carboxylicacids. Other examples of cellulose reactive groups aretetrafluorocyclobutyl carbonyl, trifluoro-cyclobutenyl carbonyl,tetrafluorocyclobutylethenyl carbonyl, trifluoro-cyclobutenylethenylcarbonyl; activated halogenated 1,3-dicyanobenzene radicals; andheterocyclic radicals which contain 1, 2 or 3 nitrogen atoms in theheterocyclic ring and at least one cellulose reactive substituent on acarbon atom of the ring.

The compounds of the invention may be in the free acid or salt form.Preferred salts are water-soluble, for example alkali metal salts,especially lithium, sodium and potassium salts, ammonium, substitutedammonium and mixed salts thereof. Preferred alkali metal salts are thosewith sodium or lithium. It is especially preferred that the compound isin the form of a mixed lithium sodium salt, because we have found thatthese salts provide prints which exhibit a high light-fastness whenincorporated into an ink jet printing ink.

Preferred ammonium and substituted ammonium salts have cations of theformula ⁺NV₄ wherein each V independently is H or optionally substitutedalkyl, or two groups represented by V are H or optionally substitutedalkyl and the remaining two groups represented by V, together with the Natom to which they are attached, form a 5- or 6-membered ring(preferably a morpholinyl, pyridinyl or piperidinyl ring).

Preferably each V independently is H or C₁₋₄-alkyl, more preferably H,CH₃ or CH₃CH₂, especially H. Thus the cation is preferably ammonium(i.e. ⁺NH₄).

Examples of cations include ⁺NH₄, morpholinium, piperidinium,pyridinium, (CH₃)₃N⁺H, (CH₃)₂N⁺H₂, H₂N⁺(CH₃)(CH₂CH₃),CH₃N⁺H₃,CH₃CH₂N⁺H₃, H₂N⁺(CH₂CH₃)₂, CH₃CH₂CH₂N⁺H₃, CH₃CH₂CH₂N⁺H₃, (CH₃)₂CHN⁺H₃,N⁺(CH₃)₄, N⁺(CH₂CH₃)₄, N-methyl pyridinium, N,N-dimethyl piperidiniumand N,N-dimethyl morpholinium.

The compounds may be converted into a salt using known techniques. Forexample, an alkali metal salt of a compound may be converted into a saltwith ammonia or an amine by dissolving an alkali metal salt of the dyein water, acidifying with a mineral acid and adjusting the pH of thesolution to pH 9 to 9.5 with ammonia or the amine and removing thealkali metal cations by dialysis.

The present invention covers all tautomeric forms of the dyes shown inthis specification, for example the hydrazo tautomers.

The compounds of the invention may be prepared using conventionaltechniques for the preparation of azo dyes. For example a suitablemethod comprises hydrolysing a compound of the Formula (7):

wherein D, Z and R¹ are as hereinbefore defined.

The hydrolysis is preferably performed by heating the compound ofFormula (7) in an aqueous medium. Preferably the hydrolysis is performedunder alkaline conditions, more preferably a pH in the range 8 to 14.The temperature during hydrolysis is preferably from 30 to 95° C., morepreferably from 40 to 90° C. The efficiency of the hydrolysis may beimproved by using a suitable catalyst, for example in the presence of acatalytic quantity of 1,4-diazabicyclo[2.2.2]octane (DABCO).

After the condensation reaction the product may be isolated byprecipitating the product as a salt from the reaction mixture forexample by the addition of a suitable alkali metal salt, especiallysodium chloride. Alternatively, the product may be isolated in its freeacid form by acidifying the reaction mixture, preferably using a mineralacid, especially hydrochloric acid. Where the product precipitates as asolid it may be separated from the mixture by filtration.

Unwanted anions may be, and preferably are removed from the product ofthe above process by dialysis, osmosis, ultrafiltration or a combinationthereof.

The product of the above process may be converted to a salt byconventional techniques as hereinbefore described.

The compound of the Formula (7) may be prepared by, for example:

(i) condensing a compound of the formula DNHR¹ with an approximatelymolar equivalent of cyanuric chloride; and

(ii) condensing the product of stage (i) with a compound of the formulaZH;

wherein D, R¹ and Z are as hereinbefore defined.

Preferably the condensation in stage (i) is performed at a temperatureof 5° C. or less. It is preferred that the pH during the condensation ismaintained above 5.5, more preferably above pH 6.

The condensation in stage (ii) is preferably performed at roomtemperature (20-30° C.). Preferably the pH during the condensation ismaintained in the range of from pH 7 to 8.5.

The compound of the formula DNHR¹ may be prepared using conventionaltechniques for the preparation of azo dyes. For example when D is of thehereinbefore Formula (2):

the compound may be prepared, for example by diazotising a compound ofthe formula ArNH₂ and coupling with a compound of the formula LNHR¹using conventional techniques.

The present invention also covers mixtures comprising two or morecompounds of the Formula (1). Furthermore, the compounds of Formula (1)may be mixed with commercially available dyes, especially those listedin the Colour Index International, to adjust the shade or otherproperties as desired.

According to a second aspect of the present invention there is provideda composition comprising:

(a) one or more compound according to the first aspect of the presentinvention (especially a magenta coloured compound); and

(b) one or more water-soluble magenta dye other than a compoundaccording to the first aspect of the invention.

The water-soluble magenta dye is preferably a xanthene dye, an azo orbis azo dye, more preferably an anionic azo or bis azo dye andespecially an azo or bis azo dye which contains one or more groupsselected from sulphonate, carboxylate and thiocarboxylate groups.

Preferred water-soluble magenta dyes include C.I. Acid Red 50, 52, 87,91, 92, 95, 249 and 289; C.I. Direct Violet 106 and 107; compounds 100to 107, 200 and 201 described on pages 8 and 9 of WO96/24636; compounds1 to 24 shown described on cols. 4 to 10 in U.S. Pat. No. 5,542,970;compounds 1 to 55 described on pages 7 to 17 of EP-A-682 088; compounds1 to 14 shown in Example 1 to 6 of EP-A-194,885; compounds 1 to 24described on pages 8 to 13 of EP-A-717 089; the compounds described inexamples 1 to 16 in cols. 5 to 11 of U.S. Pat. No. 5,262,527; and thedyes described in Examples 1 to 21 in WO 94/16021.

Especially preferred water-soluble magenta dyes for use in thecomposition according to the second aspect of the invention include C.I.Acid Red 52, C.I. Acid Red 289 or a dye of the Formula (8), (9) and (10)and salts thereof:

The dye of Formula (8) may be prepared using the method described inExample 1 of EP 0 559 310. The dye of the Formula (9) may be preparedusing the method described in Example 3 of PCT publication number WO94/16021. The dye of Formula (10) may be prepared using the methoddescribed in Example 1 of WO 96/24636.

The composition according to the second aspect of the present inventionpreferably comprises:

(a) from 1 to 99, more preferably from 3 to 70 and especially from 5 to50 parts in total of the compound(s) according to the first aspect ofthe invention; and

(b) from 99 to 1, more preferably from 30 to 97 parts and especially 95to 50 parts in total of the water-soluble magenta dye(s);

wherein the parts are by weight and the sum of the parts (a)+(b)=100.

The composition may contain a single dye of Formula (1) or a mixturethereof. Similarly, the composition may contain a single water-solublemagenta dye or a mixture of two or more water-soluble magenta dyes.

The compounds and compositions according to the first and second aspectsof the present invention may be, and preferably are, purified to removeundesirable impurities before they are incorporated into inks for inkjet printing. Conventional techniques may be employed for purification,for example ultrafiltration, reverse osmosis and/or dialysis.

According to a third aspect of the present invention there is providedan ink comprising:

(a) a compound according to the first aspect of the present invention,or a composition according to the second aspect of the invention; and

(b) a liquid medium.

Preferably component (a) of the ink is one of the preferred compounds orcompositions as hereinbefore described in relation to the first orsecond aspect of the invention. More preferably component (a) is one ormore compounds of the Formula (1) or Formula (6) or salts thereof, ashereinbefore defined.

The liquid medium preferably comprises:

(i) water;

(ii) a mixture of water and an organic solvent; or

(iii) an organic solvent free from water.

The number of parts by weight of component (a) of the ink is preferablyfrom 0.01 to 30, more preferably 0.1 to 20, especially from 0.5 to 15,and more especially from 1 to 5 parts. The number of parts by weight ofcomponent (b) is preferably from 99.99 to 70, more preferably from 99.9to 80, especially from 99.5 to 85,and more especially from 99 to 95parts. The number of parts (a)+(b) is 100.

Preferably component (a) is completely dissolved in component (b).Preferably component (a) has a solubility in component (b) at 20° C. ofat least 10%. This allows the preparation of concentrates which may beused to prepare more dilute inks and reduces the chance of thecompound(s) of component (a) of the ink precipitating if evaporation ofthe liquid medium occurs during storage.

When the liquid medium comprises a mixture of water and an organicsolvent, the weight ratio of water to organic solvent is preferably from99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from95:5 to 80:20.

It is preferred that the organic solvent present in the mixture of waterand organic solvent is a water-miscible organic solvent or a mixture ofsuch solvents. Preferred water-miscible organic solvents includeC₁₋₆-alkanols, preferably methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol andcyclohexanol; linear amides, preferably dimethylformamide ordimethylacetamide; ketones and ketone-alcohols, preferably acetone,methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscibleethers, preferably tetrahydrofuran and dioxane; diols, preferably diolshaving from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethyleneglycol, propylene glycol, butylene glycol, pentylene glycol, hexyleneglycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferablydiethylene glycol, triethylene glycol, polyethylene glycol andpolypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol;mono-C₁₋₄-alkyl ethers of diols, preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially 2-methoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol,2-[2-(2-methoxyethoxy)ethoxy]ethanol,2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether;cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone,N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclicesters, preferably caprolactone; sulphoxides, preferably dimethylsulphoxide and sulpholane. Preferably the liquid medium comprises waterand 2 or more, especially from 2 to 8, water-miscible organic solvents.

Examples of further suitable ink media comprising a mixture of water andone or more organic solvents are described in U.S. Pat. No. 4,963,189,U.S. Pat. No. 4,703,113, U.S. Pat. No. 4,626,284, EP 425,150A and U.S.Pat. No. 5,207,824.

When the liquid medium comprises an organic solvent free from water,(i.e. less than 1% water by weight) the solvent preferably has a boilingpoint of from 30° to 200° C., more preferably of from 40° to 150° C.,especially from 50 to 125° C. The organic solvent may bewater-immiscible, water-miscible or a mixture of such solvents.Preferred water-miscible organic solvents are any of the hereinbeforedescribed water-miscible organic solvents and mixtures thereof.Preferred water-immiscible solvents include, for example, aliphatichydrocarbons; esters, preferably ethyl acetate; chlorinatedhydrocarbons, preferably CH₂Cl₂; and ethers, preferably diethyl ether;and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent,preferably a polar solvent is included because this enhances solubilityof the dye in the liquid medium. Examples of polar solvents includeC₁₋₄-alcohols. In view of the foregoing preferences it is especiallypreferred that where the liquid medium is an organic solvent free fromwater it comprises a ketone (especially methyl ethyl ketone) &/or analcohol (especially a C₁₋₄-alkanol, such as ethanol or propanol).

The organic solvent free from water may be a single organic solvent or amixture of two or more organic solvents. It is preferred that when themedium is an organic solvent free from water it is a mixture of 2 to 5different organic solvents. This allows a medium to be selected whichgives good control over the drying characteristics and storage stabilityof the ink.

Ink media comprising an organic solvent free from water are particularlyuseful where fast drying times are required and particularly whenprinting onto hydrophobic and non-absorbent substrates, for exampleplastics, metal and glass.

An especially preferred ink comprises:

(a) from 1 to 10 parts in total of a compound or composition accordingto the first or second aspect of the invention;

(b) from 2 to 60, more preferably 5 to 40 parts of water-soluble organicsolvent; and

(c) from 30 to 97, more preferably 40 to 85 parts water;

wherein all parts are by weight and the sum of the parts(a)+(b)+(c)=100.

When the liquid medium in the ink comprises a mixture of water and anorganic solvent; or an organic solvent free from water, component (a) ofthe ink may comprise a compound of the Formula (A) as hereinbeforedefined in relation to the first aspect of the invention.

The inks according to the present invention may also contain additionalcomponents conventionally used in ink jet printing inks, for exampleviscosity and surface tension modifiers, corrosion inhibitors, biocides,kogation reducing additives, anti-cockle agents to reduce paper curlingand surfactants which may be ionic or non-ionic.

The pH of the ink is preferably from 4 to 11, more preferably from 7 to10.

The viscosity of the ink at 25° C. is preferably less than 50 cP, morepreferably less than 20 cP and especially less than 5 cP.

When the inks according to the invention are used as ink jet printinginks, the ink preferably has a concentration of less than 500 parts permillion, more preferably less than 100 parts per million of halide ions.It is especially preferred that the ink has less than 100, morepreferably less than 50 parts per million of divalent and trivalentmetals, wherein parts refer to parts by weight relative to the totalweight of the ink. We have found that purifying the inks to reduce theconcentration of these undesirable ions reduces nozzle blockage in inkjet printing heads, particularly in thermal ink jet printers.

A fourth aspect of the present invention provides a process for printingan image on a substrate comprising applying thereto by means of an inkjet printer an ink containing a compound according to the first aspectof the invention, a composition according to the second aspect of theinvention or a compound of the Formula (A) as hereinbefore defined inrelation to the first aspect of the invention.

The ink used in this process is preferably as defined in the thirdaspect of the present invention.

The ink jet printer preferably applies the ink to the substrate in theform of droplets which are ejected through a small orifice onto thesubstrate. Preferred ink jet printers are piezoelectric ink jet printersand thermal ink jet printers. In thermal ink jet printers, programmedpulses of heat are applied to the ink in a reservoir by means of aresistor adjacent to the orifice, thereby causing the ink to be ejectedin the form of small droplets directed towards the substrate duringrelative movement between the substrate and the orifice. Inpiezoelectric ink jet printers the oscillation of a small crystal causesejection of the ink from the orifice.

The substrate is preferably paper, plastic, a textile, metal or glass,more preferably paper, an overhead projector slide or a textilematerial, especially paper.

Preferred papers are plain or treated papers which may have an acid,alkaline or neutral character. Examples of commercially available papersinclude, HP Premium Coated Paper, HP Photopaper (all available fromHewlett Packard Inc.), Stylus Pro 720 dpi Coated Paper, Epson PhotoQuality Glossy Film, Epson Photo Quality Glossy Paper (available fromSeiko Epson Corp.), Canon HR 101 High Resolution Paper, Canon GP 201Glossy Paper, Canon HG 101 High Gloss Film (all available from CanonInc.), Wiggins Conqueror paper (available from Wiggins Teape Ltd), XeroxAcid Paper and Xerox Alkaline paper, Xerox Acid Paper (available fromXerox).

A fifth aspect of the present invention provides a substrate, preferablya paper, an overhead projector slide or a textile material, printed withan ink according to the third aspect of the present invention or bymeans of the process according to the fourth aspect of the presentinvention.

According to a sixth aspect of the present invention there is providedan ink jet printer cartridge comprising a chamber and ink, wherein theink is present in the chamber and the ink contains a compound or acomposition according to the first or second aspect of the invention.Preferably the ink is an ink according to the third aspect of theinvention.

According to an eighth aspect of the present invention there is providedan ink jet printer containing an ink jet printer cartridge, wherein theink jet printer cartridge is as defined in the seventh aspect of thepresent invention.

The invention is further illustrated by the following Examples in whichall parts and percentages are by weight unless otherwise stated.

EXAMPLE 1 Dye (1)

Dye (1) was prepared according to stages (a) to (e):

Stage (a): Preparation of1-Amino-7-(2′-carboxyphenylazo)-8-naphthol-3-,6-disulphonic Acid

Anthranilic acid (18.34 g, 0.135 mol) and sodium nitrite (9.25 g, 0.134mol) were dissolved in water (100 ml) at pH7 and added to conc. HCl (75ml) at 5C. Excess nitrite was destroyed with a small amount of sulphamicacid. This was then added to a solution of N-acetyl H acid (74.3 g,0.134 mol) in water (300 ml) at pH7. The pH was then raised to 7.5-8 andthe reaction stirred overnight. The pH was then raised to 11.5-12 withconc. NaOH liquor and mixture heated at 85° C. for 2-3 hours. The pH wasthen lowered to 3 with conc. HCl and the product precipitated with theaddition of sodium chloride. The solid precipitate was filtered off,slurried in acetone and dried to give the product (51% strength).

Stage (b)—Condensation With Cyanuric Chloride:

The product from stage (a) (10.8 g; 0.015 mol) was dissolved in water(400 mls) by addition of NaOH to pH 8.0. The mixture was cooled to <5°C. before adding cyanuric chloride (3.0 g; 0.0158 mol) in acetone (100mls). The mixture was allowed to react for 1 hour before warming to roomtemperature. NaOH was then added to the mixture until a pH of 7.0 wasreached in order to destroy excess cyanuric chloride.

Stage (i): Condensation With L-Proline

L-proline (1.9 g; 0.0165 mol) was added to the mixture in stage (b) andthe pH adjusted to 8.0-8.5 with NaOH. The reaction was complete afterapproximately 2 hours at room temperature. (Confirmed by HPLC).

Stage (d) Hydrolysis

Sodium hydroxide (46-48%) was added to the mixture from stage (1) toraise pH to 12.0-12.5 and the mixture was heated to 85° C. for 12 hours.HCl was then added to adjust the pH to 1.0 and sodium chloride was addedto approximately 15% w/w. The resulting precipitate was removed from themixture by filtration.

Stage (e): Purification

The product from stage (d) was dissolved in a small amount of water andthen re-precipitated into methylated spirit. The precipitate wasisolated by filtration and dissolved in a small quantity of water. Themixture was then added to acetone and the resulting product isolated byfiltration. The solid was dissolved in water with NaOH and the solutiondialysed to low conductivity (<100 μs). The title product was then driedin an oven at 60° C.

EXAMPLE 2

Dyes (2) to (5) of the Formula (B) were prepared using an analogousprocess to that described in Example (1) except that in stage (i) inplace of the L-proline was used the compound of the formula ZH shown inTable 1; and in stage (d) the hydrolysis was catalysed by the additionof approximately 1 g of DABCO:

TABLE 1 Dye ZH 2 Pyrrolidine 3 1,2,3,4-tetrahydroisoquinoline 42,6-dimethylmorpholine 5 3,5-dimethylpyrazole

EXAMPLE 3 Dye 6

Dye 6 was prepared using an analogous process to that described inExample 1 except that in stage (i) morpholine was used in place of theL-proline and in stage (d) the hydrolysis was catalysed by the additionof DABCO. Analysis by mass spectrometry found m/z 646 (M−H)⁻. RequiresM⁺=647.

EXAMPLE 4 Dye 7

Dye 7 was prepared as in Example 1 except that in stage (a) in place ofN-acetyl H-acid (N-acetyl-amino-8-naphthol 3:6-disulphonic acid) therewas used N-acetyl K-acid (N-acetyl 1-amino-8-naphthol-4:6-disulphonicacid) and in stage (i) 2,6-dimethyl morpholine was used in place ofL-proline and in stage (d) the hydrolysis was catalysed by the additionof DABCO. Analysis by mass spectrometry found m/z 674 (M−H)⁻. RequiresM⁺=675.

EXAMPLE 5 Dye 8

Dye 8 was prepared as for Dye 7 in Example 4 except that morpholine wasused in place of 2,6-dimethyl morpholine. Analysis by mass spectrometryfound m/z 646 (M−H)⁻. Requires M⁺=647.

EXAMPLE 6

Dye 9 was prepared according to stages (a) to (e) below:

Stage (a): Preparation of1-Amino-7-(2′-sulphophenylazo)-8-naphthol-3,6-disulphonic Acid

Dye 9 was prepared using an analogous process to that described inExample 1 except that in stage (a) orthanilic acid (2-amino benzenesulphonic acid) was used in place of anthranilic acid.

Stage (b)—Condensation With Cyanuric Chloride:

The product from stage (a) (38.4 g; 0.05 mol) was dissolved in water(400 ml) by the addition of NaOH to pH 6.0. The mixture was cooled to<5° C. before adding cyanuric chloride (9.7 g; 1.05 mol) in acetone (100ml). The mixture was allowed to react for 2 hours, then further cyanuricchloride (1.5 g) in acetone (15 ml) was added before warming to roomtemperature. The reaction was complete after stirring for a further 2hours. Sodium chloride was then added and the precipitated solidfiltered off, washed with brine, acetone and filtered off.

Stage (i): Condensation With 2,6-Dimethyl Morpholine

2,6-Dimethyl morpholine(2.87 g; 0.19 mol) was added to the solid (20 g)from stage (b) in water (250 mls) and stirred at pH 7.5-8.0. Thereaction was complete after approximately 14 hours at room temperature(confirmed by HPLC). The reaction mixture was evaporated to a lowvolume, diluted with acetone (400 ml) and the precipitated solidfiltered off and washed with acetone (100 mls).

Stace (d) Hydrolysis

Sodium hydroxide (46-48%) was added to the damp paste (32 g) from stage(i) in water (150 ml) to raise the pH to 12.0-12.5 and the mixture washeated to 80° C. for 7 hours. HCl was then added to adjust the pH to8.5. The reaction mixture was concentrated to a low volume (50 ml) andacetone (400 ml). The resulting precipitate was removed from the mixtureby filtration and washed with acetone.

Stage (e): Purification

The product from stage (d) was dissolved in water with NaOH and thesolution dialysed to low conductivity (<100 μs). The title product wasthen dried in an oven at 60° C.

Analysis by mass spectrometry found m/z 732 (M−H+Na)⁻. Requires M⁺=711.

EXAMPLE 7 Dye 10

Dye 10 was prepared as in Example 6 above except that in stage (1)morpholine was used in place of 2,6-dimethyl morpholine. Found m/z 682(M−H)⁻. Requires M⁺=711.

EXAMPLE 8 Dye 11

Dye 11 was prepared using an analogous process to that described inExample 1 except that in stage (a) 2-amino-5-methylbenzene sulphonicacid was used in place of anthranilic acid and in stage (i) morpholinewas used in place of L-proline and in stage (d) the hydrolysis wascatalysed by the addition of DABCO. Analysis by mass spectrometry foundm/z 696 (M−H)⁻. Requires M⁺=697.

EXAMPLE 9 Dye 12

Dye 12 was prepared using an analogous process to that described inExample 1 except that in stage (a) 2-amino-5-methylbenzene sulphonicacid was used in place of the anthranilic acid and in stage (i)2,6-dimethyl morpholine was used in place of L-proline and in stage (d)the hydrolysis was catalysed by the addition of DABCO. Analysis by massspectrometry found m/z 724 (M−H)⁻. Requires M⁺=725.

EXAMPLE 10 Dye 13

Dye 13 was prepared using an analogous process to that described inExample 1 except that in stage (a) Tobias acid(2-napthylamine-1-sulphonic acid) was used in place of anthranilic acidand in stage (i) morpholine was used in place of L-proline and in stage(d) the hydrolysis was catalysed by the addition of DABCO. Analysis bymass spectrometry found m/z 732 (M−H)⁻. Requires M⁺=733.

EXAMPLE 11 Inks and Inkjet Printing

The dyes described in Examples 1 to 10 were formulated into inks bydissolving 3.5 parts of the dye in 96.5 parts of a medium (adjusted topH 9.5 with ammonium hydroxide) comprising:

5 parts 2-pyrrolidone;

5 parts thiodiglycol

2 parts Surfynol 465 (a non-ionic surfactant available from Air ProductsInc.); and

88 parts water.

The resulting solution was filtered through a 0.45 μm filter. When thedyes were incorporated into an ink medium and printed onto paper usingan ink jet printer the resulting prints were a bright magenta shadewhich exhibited a high light-fastness.

EXAMPLE 12 Inks

The inks shown in tables 2, 3 and 4 may be prepared by dissolving thedye shown in columns 2 and 3 in the liquid medium shown in columns 4 to14 by adjusting the pH of the ink to that indicated in the last columnusing a suitable base (for example NaOH). The resulting solution is thenfiltered to give the final ink.

The inks may be applied to paper by thermal or piezo ink jet printing.

The following abbreviations are used in Tables 2, 3 and 4:

PG = propylene glycol DEG = diethylene glycol NMP = N-methyl pyrrolidoneTFP = 2,2,3,3-tetrafluoropropanol CYC = cyclohexanol 2P = 2-pyrrolidoneP12 = propane-1,2-diol UR = Urea CET = cetyl ammonium bromide PHO =Na₂HPO₄ and TBT = tertiary butanol TDG = thiodiglycol GLY = glycerolP-1,5 = Pentane-1,5-diol H-1,6 = Hexane 1,6-diol CAP = caprolactoneCAP-L = caprolactam TEA = triethanolamine EG = ethylene glycol BUT =γ-butyrolactone DEG-MBE = diethylene glycol monobutyl ether PEG 200 =Polyethylene glycol (average molecular weight of 200)

TABLE 2 Dye Ink Dye Content Water PG DEG NMP P-1,5 TEA CYC BUT CAP EGCAP-L pH  1 1 3.0 90 5 4.8 0.2 8  2 2 10.0 85 3 3 3 5 9  3 2 2.1 91 8 11 9.5  4 3 3.1 86 5 0.2 4 4.8 10  5 4 1.1 81 9 0.5 0.5 11  6 5 2.5 60 415  3 3 6 9 4 7.5  7 4 5 65 20  5 10 5 13  8 3 2.4 75 5 4 5 6 5 12  9 34.1 80 3 5 2 9.7 0.3 13 10 1 3.2 65 5 4 6 5 4 5 9 11 1 5.1 96 4 6 9 12 510.8 90 5 5 9 13 5 10.0 80 2 6 2 5 1 9.5 14 3 1.8 80 5 4 8.5 15 5 2.6 8411 15  9 16 5 3.3 80 2 10 2 5 6 9 17 5 12.0 90 7 0.3 2.7 10 18 2 5.4 692 20  2 1 3 3 11

TABLE 3 Dye Ink Dye Content Water GLY DEG NMP CET TBT TDG UR PHO 2P PI2pH 19 1 3.0 80 15 0.2 4.8 9 20 2 9.0 90 5 1.2 5 9 21 3 1.5 85 3.8 5 0.164.64 0.2 10 22 4 2.5 90 6 3.88 0.12 9.5 23 5 3.1 82 4 8 0.3 5.7 13 24 30.9 85 10 4.8 0.2 12 25 2 8.0 90 4.7 5 0.3 7.6 26 1 4.0 70 10 4 1 4 11 827 2 2.2 75 4 10 3 2 6 8.4 28 1 10.0 91 6 3 9.0 29 5 9.0 76 9 7 2.050.95 5 9.4 30 3 5.0 78 5 11 6 9.5 31 1 5.4 86 7 7 9 32 1 2.1 70 5 5 50.1 0.2 0.1 5 0.1 9.5 10 33 3 2.0 90 10 9.5 34 2 2 88 2 10 10.0 35 4 578 5 12 5 11.5 36 2 8 70 2 8 15 5 8.5 37 1 10 80 8 12 9.5 38 4 10 80 109.7

TABLE 4 Dye PEG DEG- Ink Dye Content Water 200 MBE NMP H-1,6 TEA TFP BUTCAP EG CAP-L pH 39 1 2.0 80 5 6 4 5 9.0 40 2 3.0 90 5 4.8 0.2 10.0 41 310.0 85 3 3 3 5 1 10.5 42 4 2.1 91 8 1 9.5 43 5 3.1 86 5 0.2 3.8 5 9.044 3 1.1 81 9 0.5 0.5 9 9.0 45 1 2.5 60 4 15  3 3 6 5 4 9.5 46 3 5 6520  10 8.5 47 5 2.4 75 5 4 5 6 5 11.5 48 5 4.1 80 3 5 2 9.7 0.3 12 49 13.2 70 5 4 6 5 4 6 5 9.0 50 1 5.1 96 4 8.6 51 1 10.8 90 5 5 9.5 52 210.0 80 2 6 2 5 1 4 9.8 53 3 1.8 80 5 15  10.3 54 4 2.6 84 11 5 11 55 53.3 80 2 10 2 6 12 56 4 12.0 90 7 0.3 2.8 9.0 57 2 5.4 69 2 20  2 1 3 39.0 58 2 6.0 91 4 5 9.5

What is claimed is:
 1. A monoazo compound of the Formula (1) and saltsthereof:

wherein: D is the residue of a mono-azo chromophore; Z is an optionallysubstituted nitrogen containing heterocyclic group; R¹ is H oroptionally substituted alkyl; the dyes of Formula (1) being free fromfibre reactive groups; provided that the compound of Formula (1) isother than the compound of Formula (A):


2. A compound according to claim 1 wherein Z is attached to the triazinering in Formula (1) by a bond to a nitrogen atom in the heterocyclicgroup.
 3. A compound according to either claim 1 or claim 2 wherein Z isfree from primary and secondary amino groups.
 4. A compound according toclaim 1 or claim 2 wherein the compound of Formula (1) is of the Formula(6) or a salt thereof:

wherein: Ar¹ is optionally substituted phenyl or optionally substitutednaphthyl; Z¹ is an optionally substituted nitrogen containingheterocyclic group which is attached to the triazine ring by a bond to anitrogen atom in the heterocyclic group; R² is H or C₁₋₄-alkyloptionally substituted by —OH, —COOH or —SO₃H; and t is 0 or
 1. 5. Acomposition comprising: (a) one or more compounds according to claim 1;and (b) one or more water-soluble magenta dyes other than a compoundaccording to (a).
 6. An ink comprising: (a) a compound according toclaim 1; and (b) a liquid medium.
 7. An ink comprising: (a) a compoundof the Formula (A) as defined in claim 1; and (b) a liquid mediumcomprising a mixture of water and an organic solvent; or an organicsolvent free from water.
 8. A process for printing an image on asubstrate comprising applying thereto by means of an ink jet printer anink comprising a compound according to claim
 1. 9. A substrate printedwith an ink according to claim 6 or claim
 7. 10. An ink jet printercartridge comprising a chamber and ink, wherein the ink is present inthe chamber and the ink contains a compound according to claim
 1. 11. Anink jet printer containing an ink jet printer cartridge, wherein the inkjet printer cartridge is as defined in claim
 10. 12. An ink comprising:(a) a composition according to claim 5; and (b) a liquid medium.
 13. Aprocess for printing an image on a substrate comprising applying theretoby means of an ink jet printer an ink comprising a composition accordingto claim
 5. 14. A process for printing an image on a substratecomprising applying thereto by means of an ink jet printer an inkcomprising a compound of the Formula (A) as defined in claim
 1. 15. Asubstrate printed with an ink according to claim 6 or claim 7 using anink jet printer.
 16. An ink jet printer cartridge comprising a chamberand ink, wherein the ink is present in the chamber and the ink containsa composition according to claim
 5. 17. An ink jet printer containing anink jet printer cartridge, wherein the ink jet printer cartridge is asdefined in claim 16.